VALIDATION OF AUTOMATIC PROCESS SAMPLING SYSTEMS

Validation of automatic process sampling systems is becoming of increasing importance as process analysers are utilised for quality control and assurance. Sampling systems are considered in four convenient categories: (A) Those sampling essentially non-reactive homogeneous liquids and gases, which remain so within the operating temperature and pressure ranges of the process and sampling system. (B) Those sampling ''homogeneous'' gases and liquids containing reactive or time unstable components. (C) Those sampling multi-phase or other heterogeneous materials. (D) Those sampling to agreed national or international standards. This paper examines validation in categories B and C and suggests routes that may be followed to achieve maximum accuracy from the whole analytical system, including sampling system design, independent sampling, limiting conditions, internal standardisation, stream parameter comparison and mass balancing. It will also briefly consider time validity in all four categories.